Technical Field
Embodiments of the present disclosure are directed to methods and systems that can automatically extract grammatically well-formed statements from a complex sentence that are suitable as claim candidates of a debatable topic.
Discussion of the Related Art
Decision support systems provide an automatic way for the compilation of useful information to make decisions. One method of decision making is to analyze the pros- and cons- of alternative actions that can meet decision objectives from different perspectives. Debating is an example of decision making where arguments that sustain or contradict a topic can help clarify and support deliberation. Arguments, also called claims, are short statements that are expressive enough to adopt a clear position on a specific topic. Automatic claim extraction is useful for topics that are evolving very quickly or have a wide variety of perspectives, i.e. are subjective.
A claim is (A) a generic, concise statement that (B) directly supports or contests a specific topic. This definition covers two aspects of a claim: a syntactic aspect (A) and a semantic aspect (B).
A claim should be an intelligible and coherent utterance, easy to understand when taken out of its immediate context, such as a sentence or paragraph, but provided with the topic that it either contests or supports.
In the context of a debatable topic, a claim expresses a specific position on some doubtful or controversial issue that an arguer wants an audience to accept. That means that additional information, such as additional verbal phrases and arguments, to support or contest the specific issue or subject are provided.
In natural languages, propositions, also called clauses, generally represent the basic unit for conveying information about a predicate of a subject. A clause is a grammatical unit that includes, at a minimum, a predicate and an explicit or implied subject, and expresses a proposition. An independent clause is a simple sentence and can stand on its own. A dependent clause cannot stand on its own, but needs an independent clause to complete the sentence. The table of FIG. 1 illustrates some examples of dependent and independent clauses. A clause generally includes at least a subject and a verb (S-V). There are 7 basic clause patterns in English: SV, SVO, SVC, SVA, SVOO, SVOA and SVOC, where C is a complement and A is an adverbial, of which only the first pattern does not align with the requirements of a claim.
Clauses can be combined in different ways in a sentence to express related information, which determines the complexity of a sentence: there are simple sentences, which have one independent clause, compound sentences, which have two or more independent clauses, and complex sentences, which have at least an independent clause and one or more dependant clauses.
The task of well-structured claim candidate identification, according to part A of the definition, can therefore be translated into a combination of clause extraction (conciseness), and their integration into coherent statements which are filtered by claim-related constraints (generality).